Turnip crinkle virus targets host ATG8 proteins to attenuate antiviral autophagy

Autophagy has emerged as a central player in plant virus disease and resistance. In this study we have addressed the potential roles of autophagy in Turnip crinkle virus (TCV) infection. We found that autophagy attenuates disease severity and contributes to resistance against TCV by limiting virus accumulation. These autophagy-dependent disease phenotypes intensify further when combined with defects in RNA silencing, suggesting that these two major defence pathways are largely uncoupled in TCV disease. Intriguingly, as a counterdefence, TCV employs the viral silencing suppressor protein P38 to suppress antiviral autophagy, likely by directly sequestering ATG8 proteins. This strategy appears to be novel for plant viruses, yet resembles mechanisms described for other pathogen classes. Together, these results broaden our understanding of autophagy in plant virus disease, and strengthens our view of virus-specific adaptation to the autophagy pathway.